staging: xgifb: remove extra parentheses around right bit shift operations

Removes extra parentheses around bitwise right shift operations.
The cases handled here are when resultant values are assigned to
variables. The issue was detected and resolved using the following
coccinelle script:

@@
expression e, e1;
constant c;
@@

e =
-(e1
+e1
>>
-c);
+c;

@@
identifier i;
constant c;
type t;
expression e;
@@

t i =
-(e
+e
>>
-c);
+c;

@@
expression e, e1;
identifier f;
constant c;
@@

e1 = f(...,
-(e
+e
>>
-c)
+c
,...);

Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>